org.apache.directory.api.ldap.model.cursor.DefaultClosureMonitor Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*
*/
package org.apache.directory.api.ldap.model.cursor;
/**
* A basic ClosureMonitor that simply uses a boolean for state and a cause
* exception.
*
* Note that we consciously chose not to synchronize close() operations with
* checks to see if the monitor state is closed because it costs to
* synchronize and it's OK for the Cursor not to stop immediately when close()
* is called.
*
* @author Apache Directory Project
*/
public class DefaultClosureMonitor implements ClosureMonitor
{
/** Tells if the monitor is closed or not */
private boolean closed;
/** If we get an exception, the cause is stored in this variable */
private Exception cause;
/**
* {@inheritDoc}
*/
@Override
public final void close()
{
// state check needed to "try" not to overwrite exception (lack of
// synchronization may still allow overwriting but who cares that much
if ( !closed )
{
// not going to sync because who cares if it takes a little longer
// to stop but we need to set cause before toggling closed state
// or else check for closure can throw null cause
cause = CursorClosedException.INSTANCE;
closed = true;
}
}
/**
* {@inheritDoc}
*/
@Override
public final void close( final String cause )
{
// state check needed to "try" not to overwrite exception (lack of
// synchronization may still allow overwriting but who cares that much
if ( !closed )
{
// not going to sync because who cares if it takes a little longer
// to stop but we need to set cause before toggling closed state
// or else check for closure can throw null cause
this.cause = new CursorClosedException( cause );
closed = true;
}
}
/**
* {@inheritDoc}
*/
@Override
public final void close( final Exception cause )
{
// state check needed to "try" not to overwrite exception (lack of
// synchronization may still allow overwriting but who cares that much
if ( !closed )
{
// not going to sync because who cares if it takes a little longer
// to stop but we need to set cause before toggling closed state
// or else check for closure can throw null cause
this.cause = cause;
closed = true;
}
}
/**
* {@inheritDoc}
*/
@Override
public final Exception getCause()
{
return cause;
}
/**
* {@inheritDoc}
*/
@Override
public final boolean isClosed()
{
return closed;
}
/**
* {@inheritDoc}
*/
@Override
public void checkNotClosed() throws CursorClosedException
{
// lack of synchronization may cause pass but eventually it will work
if ( closed )
{
throw new CursorClosedException( cause.getMessage() );
}
}
}